The Discovery Deep Seas floats 190 miles south of New Orleans. (Courtesy of Paul Taggart.)

The easy oil is gone. To get to the new oil, you board a yellow Bell 407 helicopter outside New Orleans and fly south, touching down 140 miles offshore, on a ship that’s drilling holes in the seabed nearly a mile below.

Along the way, you fly down a 50-year timeline of American offshore oil extraction. Through the glass panel at your feet, you watch the delta slide by with its flat islands of green and its fishing camps, occasionally passing the remains of a barge rig – the first and simplest waterborne oil rigs, which simply settled in the mud and drilled. After the barrier islands come the brown waters of the continental shelf of the Gulf of Mexico. Here, the platforms increase in number but are only slightly more complicated; of the roughly 4,000 platforms in the gulf, most are simple scaffolds standing on the bottom in 30 to 200 feet of water.

[Click here for views of the Discoverer Deep Seas and its oil-extracting equipment and monitors.]

But the barge rigs and the fixed-leg platforms are the past. So you keep flying, and the rigs grow scarcer but larger, until you leave the silty waters and hit the blue of the deep water, which shimmers like an opal lit from within.

Out here, 4,300 feet above the seafloor, floats Discoverer Deep Seas. Leased by Chevron, it’s a ship that would have been too expensive to use 10 years ago, a ship that represents 20 years of advances in the art and science of oil extraction. It’s not particularly beautiful. With its derrick amidships and its rusty waterline, Deep Seas looks like a ghost tanker trying to make off with the Eiffel Tower. But it is a breathtaking expression of ingenuity, and a glimpse of what we’ll increasingly have to do to get energy.

The ship is so big that my incomplete tour will take a day. It’s 835 feet long – on end, it would be the height of an 80-story skyscraper – and 125 feet wide. Because it is so tightly packed with machinery, a visitor winds through Deep Seas rather than walking its perimeter, as one might on a cruise ship, and never gains a full sense of its size.

My guide is Eddie Coleman, the lead drill-site manager on Deep Seas. A quiet Texan in a denim Chevron shirt and jeans, Coleman has spent the past 32 years offshore, working two weeks on and two weeks off, shuttling between his home of Brookhaven, MS, and platforms and drillships progressively farther offshore and more advanced. Like most of the people I meet in this business, he says he wouldn’t want to do anything else.

Coleman is in a decent mood, but he could be happier. Last night, the drilling in a well that Chevron calls PS002 stalled at 20,351 feet. Deep Seas doesn’t produce oil; it drills for it, capping the wells and leaving them to be put into “production” by equally expensive and complicated floating platforms. The oil field that Deep Seas is exploring is called Tahiti, and it’s about 24,000 feet below a 5-by-1.5-mile section of seafloor leased from the Minerals Management Service of the U.S. government, in an area known as Green Canyon. PS002 is the second well of a scheduled six, and the whole field is slated to go into production in 2008. Chevron hopes to pump 125,000 barrels a day out of Tahiti.

Pumping is a long way off, though, and now the drilling has stopped, too. “We tagged something,” explains Coleman, “but we’re not sure what. So we’re tripping right now.” To “trip” means to bring the drill bit back up or send it back down. Coleman and a team back in Houston have decided that the casing, the tube that is dropped down in increasingly narrow segments as drilling progresses, in order to maintain the integrity of the well, has probably gotten out of round or developed a spur of some kind. So once they’ve tripped the bit back up, they’ll send down a mill to bore out the casing. And when they’ve retracted the mill, the bit will have to be tripped down again.

The trip takes about 12 to 13 hours either way, and it’s expensive. Deep Seas is leased from a company called Transocean, and the daily rent is about $250,000. With the cost of labor and equipment, drilling in Green Canyon costs Chevron around $500,000 a day. Casing, for instance, costs around $100 per foot. The drill bits run around $80,000 each, and there are 140 to 175 well-paid people onboard, from cooks to highly trained geologists. Developing the Tahiti field will cost about $3.5 billion.

Because of the resulting financial pressure, Deep Seashasn’t been back to shore since it was launched five years ago. Every six months or so, a supply ship pulls up alongside and pumps a million gallons of diesel onboard. The fill-up takes about 24 hours. The diesel runs six generators, which send five megawatts of power to each of six electric omnidirectional thrusters, which keep the ship in position. On a calm day like this, the thrusters, fed by GPS data and overseen by a team of dynamic-positioning operators on the bridge, keep the 100,000-metric-ton ship essentially stationary; it drifts only by inches over the well below.